In 2176, the asteroid Ganymed will come as close as 0.02868 AU (4,290,000 km / 2,670,000 mi) from Mars. That's pretty close to Mars imho. Can Mars' gravity alter Ganymed's orbit significantly in 2176 and if so, how much would it change? Just curious. Ganymed is a near-Earth object after all, and one at global killer size.

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    $\begingroup$ Would you mind adding a link to the source for this close pass? $\endgroup$ – Connor Garcia Jan 7 at 15:48
  • $\begingroup$ @ConnorGarcia Why, don't you believe me? If not, just assume it's a hypothetical encounter: "What would happen if Ganymed came as close as 0.02868 AU from Mars?" A source is unnecessary to answer the question (except for orbital direction which I dunno either). $\endgroup$ – Greenhorn Jan 7 at 16:13
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    $\begingroup$ I believe you, but I am curious if there is more information like the angle between their orbital paths or an exact date, etc... More information might help narrow the scope of the answer. $\endgroup$ – Connor Garcia Jan 7 at 16:20
  • $\begingroup$ @ConnorGarcia ssd.jpl.nasa.gov/sbdb.cgi?sstr=Ganymed;cad=1#cad $\endgroup$ – Greenhorn Jan 7 at 16:27
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    $\begingroup$ How do you define a "significant" change? $\endgroup$ – Jonas Jan 8 at 17:03

Ganymed's Mars approach in 2176 is only moderately close: 4.4 times Mars's Hill sphere radius or 11 times the average Earth-Moon distance. JPL HORIZONS predicts these heliocentric orbital elements (J2000) before and after the encounter:

Date e a i Ω ω
2176-12-06 0.525078 2.65922 au 27.7778° 212.085° 136.031°
2176-12-26 0.525093 2.65922 au 27.7772° 212.085° 136.025°

The change is slight.

With respect to Potentially Hazardous Asteroid criteria, Ganymed is large enough (H = 9.4 < 22) but can't get close enough to Earth (MOID = 0.34 au > 0.05 au).


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